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| Thorianite
is named for its chemical composition containing thorium,
a highly radioactive element,
which was named for Thor, the Scandinavian god of war.
| Discovered
in 1904;
IMA
status: Valid (pre-IMA; Grandfathered) |
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Composition: |
Thorium |
87.88 % |
Th |
100.00 % |
ThO2 |
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Oxygen |
12.12 % |
O |
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100.00 % |
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100.00 % |
= TOTAL OXIDE |
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Classification
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Mineral
Classification: |
Oxides
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Strunz 8th
Ed. ID:
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4/D.31-50
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Nickel-Strunz 10th
Ed. ID:
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4.DL.05
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4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar L : With large (+- medium-sized) cations; fluorite-type structures
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Related
to: |
Thorianite-Uraninite Series.
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Varieties: |
Aldanite,
Uranothorianite
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Synonyms: |
α-Thorianite,
β-Thorianite, γ-Thorianite, Uraninitte (of Coomaraswamy)
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Crystal
Data
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Crystallography:
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Isometric
- Hexoctahedral
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Crystal
Habit:
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Cubic crystals, rarely
modified by {111} and {113}, to 9 cm, usually rounded to some degree (water worn)
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Twinning:
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Penetration twins on {111} very common
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Physical
Properties
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Cleavage: |
Poor
on {001}
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Fracture: |
Irregular/Uneven
to Sub-Conchoidal
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Tenacity:
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Brittle
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Moh's
Hardness: |
6.5 - 7.0
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Density:
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9.70
- 9.80 (g/cm3)
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Luminescence:
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Radioactive
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Radioactivity:
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Very
Strong;
GRapi = 1,505,305.18 (Gamma Ray American Petroleum Institute Units)
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Health
Warning: |
Contains thorium - always wash hands after handling. Avoid inhaling dust when
handling or breaking. Never lick or ingest. Avoid prolonged exposure in
proximity of the body. Store away from inhabited areas. |
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Optical
Properties
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Color: |
Black,
brownish black, dark gray, dark reddish brown, may have
a bronzy tarnish; in transmitted light, dark brown,
reddish brown, greenish; gray with red-brown internal
reflections in reflected light. |
Transparency: |
Opaque;
Transparent in very thin fragments |
Luster: |
Submetallic
when fresh, altering to Resinous |
Refractive
Index: |
2.20
- 2.35 Isotropic; may show anomalous anisotropism
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Birefringence: |
0.000;
Isotropic |
Dispersion: |
n/a
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Pleochroism: |
n/a
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Anisotrophism: |
May show anomalous anisotropism;
red-brown
internal reflections in reflected light.
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Occurances
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Geological
Setting: |
An
accessory mineral in granite pegmatites, more rarely
in carbonatites or serpentinites; commonly detrital
in heavy mineral concentrates. |
Common
Associations: |
Thorite,
Zircon, Ilmenite, Cassiterite, Allanite (Sri Lanka);
Phlogopite, Diopside, Spinel (Andolobe, Madagascar)
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Common
Impurities: |
U,
Ce, La, Pb, TR |
Type
Locality: |
Balangoda, Ratnapura, Sabaragamuwa Province, Sri
Lanka |
Year
Discovered: |
1904
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View
mineral photos: |
Thorianite
Mineral Photos and Locations |
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More
Information
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Mindat.org
Webmineral.com
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Thorianite
is a rare thorium oxide mineral that is strongly radioactive
due to its throium content. It is more stongly radioactive
than Thorite,
another thorium mineral that contains both thorium and
uranium. Thorium was originally discovered by Ananda Coomaraswamy in 1904 as Uraninite, but recognized as a new species by Wyndham
R. Dustan. Thorianite is a rare mineral, but an even
rarer as a faceted gem. Thorianite is usually black
with a submetallic luster and Mohs hardness of 6.5 -
7.0.
Thorianite is mainly for collectors
of rare and unusual gems, black
gems or
radioactive
gems. Thorianite
is a highly radioactive mineral and should be stored
away from other minerals and gems that might be damaged
by radioactivity. Human contact and exposure to Thorianite
mineral specimens or gems should be limited!
Current sources are Balangoda, Ratnapura, Sabaragamuwa Province, Sri
Lanka; Betroka,
Madagascar, where very large crystals are found; and
other locations including South Africa, Russia, USA
and Canada.
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Thorianite
gems for sale:
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Gem:
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Thorianite |
Stock
#:
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THORN-001 |
Weight:
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1.9540
ct |
Size: |
5.53
x 4.98 x 3.39 mm |
Shape: |
Cut-corner
rectangle |
Color: |
Black |
Clarity: |
Opaque |
Origin: |
Balagoda,
Sri Lanka |
Treatment: |
None
(natural) |
Price: |
SOLD
(but we have others) |
Pictures
are of the actual gem offered for
sale. Gem images are magnified to
show detail. |
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An
extremely rare gem from
Balangoda, Ratnapura, Sabaragamuwa Province, Sri
Lanka.
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